1. Field of the Invention
The present invention relates to an automatic following travel system wherein, among a plurality of queued vehicles, a leading vehicle positioned at the front is operated by an operator, and following vehicles positioned behind the leading vehicle automatically follow the leading vehicle so as to conduct travel in file.
This application is based on Japanese Patent Application No. 11-90263, the contents of which are incorporated herein by reference.
2. Background Art
As is commonly known, systems have been proposed wherein small electric vehicles are used in common by a plurality of users in a defined region, and thereby, efficient use of the vehicles is achieved, and by means of this, problems such as congestion and insufficient space are relieved, and a savings in resources and energy, as well as an improvement in environmental contamination, are achieved.
In other words, dedicated parking, termed ports, is established at a number of places within a limited region, and users are able to freely borrow vehicles from these ports, and furthermore, after the use of the vehicles, the vehicles may be returned to the ports. By means of this, users are able to employ the vehicles only when they are required. Furthermore, if there are a large number of ports, it will not be necessary to search for parking spaces or to park along the side of the road, and it is thus possible to alleviate congestion.
However, in such a system, as a result of the locations at which the ports are established or the like, there are concerns that vehicles may become concentrated at some ports, while at other ports, vehicles will become insufficiently available.
Techniques have been proposed for moving a plurality of vehicles efficiently between ports so as to easily remedy this imbalance of vehicles existing between ports (for example, in Japanese Patent Application, First Publication, No. Hei 5-170008). In this technique, among a plurality of queued vehicles, only the leading vehicle, which is positioned at the front, is manually operated by an operator, and the operation of the following vehicles is automatically controlled based on data relating to the amount of driving operation of the leading vehicle which is transmitted from the leading vehicle. By means of this, driving is controlled so that the following vehicles trace the same track as the leading vehicle, and as a result, a state is realized in which a series of vehicles travel in such a manner as to form a file with the leading vehicle in the front (travel in file). At this time, because the operation of the following vehicles is automatically controlled, unmanned operation is possible, and it is possible to reduce the number of humans involved.
In order to realize the travel in file described above, it is necessary to recognize a series of vehicles as a group of vehicles, and to conduct automatic operation control with respect to the vehicles recognized as being members of the group of vehicles by means of data related to the amount of driving operation similar to that of the leading vehicle, or to conduct positional control for maintaining a constant distance between vehicles.
Accordingly, when travel in file is terminated, if the recognition of a series of vehicles as vehicles within a single group is canceled, then simultaneously, the automatic operation control and the positional control of the following vehicles is also canceled, and in particular, in cases such as that in which traveling in file is terminated in an inclined traveling path, it becomes impossible to maintain a constant position of the following vehicles.
Furthermore, in the automatic operation control such as that described above, in order that the following vehicles be satisfactorily able to trace the track of the leading vehicle, during travel in file, operations identical to predetermined operations in the leading vehicle are carried out in the following vehicles when the following vehicles pass through a position which is the same as that at which the predetermined operations were conducted in the leading vehicle. However, when this type of control is applied to operations such as parking braking, then during the formation of the traveling in file, even if the leading vehicle releases its parking braking so as to initiate forward progress, the following vehicles are incapable of releasing their parking braking until they reach the position of the leading vehicle, and they are not capable of initiating forward progress. Furthermore, if, in order to avoid this problem, control content is simply added in which the following vehicles release their parking braking at the same time at which a leading vehicle releases its parking braking, then if travel in file is to be initiated on an inclined path, when a state is produced in which the parking braking of the leading vehicle is released prior to the initiation of the control by which a constant distance is maintained by the following vehicle, then a constant position of the following vehicles cannot be maintained.